What is Unity? Why add Unity physics to games? What is the objective of the course?

• Unity is a powerful interactive development platform
• Unity physics offers fun, realistic, and engaging game mechanics
• The expert instructor leads you to master the many facets of Unity physics

What are the major concerns of any physics system?

• Learn about its integration, learn how physics simulation fits into our game world
• Collision Detection detects which objects are overlapping
• Collision Resolution handles the realistic reaction (for example, bouncing) for each overlap

What are the unique features and benefits of Unity’s physics system?

• Unity is a powerful interactive development platform and offers great physics simulation
• Unity uses various third-party physics libraries with unique pros/cons
• Unity is vastly improving the physics systems with each update

What are the Unity project settings and which values are most important for physics?

• Unity Project settings are high-level adjustments to the graphics, physics, and other details of the published player
• The gravity and default material are important settings
• 2D Physics settings are separate from 3D, adjust as per what is appropriate for your project

What is the Unity physics lifecycle and how can we manipulate time?

• Physics is based on the MonoBehaviour lifecycle
• C# can hook into the relevant events
• For advanced timing needs, Physics.Simulate can be called manually

What is the Rigidbody2D component and which of its properties are most important for us to use?

• The Rigidbody2D component enables physical behavior for a GameObject
• With a Rigidbody2D, the GameObject will immediately respond to gravity
• Body Type and Mass are among the most important Rigidbody2D properties

What is the Collider2D component and which of its properties are most important for us to use?

• The Collider2D component defines the shape of an object for the purposes of physical collisions
• Circle Collider2D and Box Collider2D are among the most popular types
• IsTrigger is an important property which determines if the collider is solid or not

What are 2D Effectors and why are they useful?

• The 2D Effector component directs the forces of physics when colliders make contact
• 2D Effectors give fine control over friction and other forces
• 2D Effectors can be used for explosions, conveyor belts, platforms, and more

What are 2D joints and why are they useful?

• The Joint2D component maintains a positional relationship with one or more GameObjects
• The HingeJoint2D is useful to create doors, bridges, and more
• 2D joints are useful to mimic real-world objects or to add unique gameplay

What is unique about the Sprite Shape and how does it relate to physics?

• Sprite Shape gives the freedom to create rich free-form, organic 2D environments, straight in Unity
• The Sprite Shape is a preview feature in Beta and requires simple, additional installation
• Sprite Shapes generate appealing visuals, as well as, colliders for full physics simulation

How does Unity 3D physics compare to 2D physics and what is unique in 3D?

• The principles, components, naming, and C# code for 2D and 3D are similar, but not identical
• Both 2D and 3D support Rigidbody, collider, joints, and physics material concepts
• Only 2D has physics Effectors, whereas 3D has ragdoll physics

What is the physics material asset, how, and when do we use it?

• The physics material asset describes how to handle colliding objects (friction and bounciness)
• It is optional and may be added to the Rigidbody, in both 2D and 3D
• Use it when your game physics needs custom friction and bounciness

What are 3D joints and why are they useful?

• The 3D Joint component maintains a positional relationship with one or more GameObjects
• The HingeJoint3D is useful to create chains
• 3D Joints are useful to mimic real-world objects or to add unique gameplay

What is Ragdoll physics and how do we use it?

• Ragdoll physics is realistic physics movement of an unconscious humanoid character model
• It is useful for showing the reaction to a character being killed or knocked unconscious
• Use the Unity ragdoll wizard window to set up a new character model

What is Unity Terrain and how do we create Unity Terrain with physics support?

• The realistic physics interaction between the organic earth surface and other GameObjects is called Terrain physics
• Create a new Terrain through the Unity Menu: GameObject -> 3D Object -> Terrain
• Terrain physics is supported automatically via the Terrain Collider component

What are the 3 OnCollision events, and why are they useful?

• OnCollisionEnter and OnCollisionExit happen at the start and end of the collision, whereas, OnCollisionStay repeats during the collision
• OnCollision events are useful to detect collisions between Rigidbodies
• The Collision.gameObject property can be checked to know what did one hit

What are the 3 OnTrigger events, and why are they useful?

• OnTriggerEnter and OnTriggerExit happen at the start and end of the intersection, whereas, OnTriggerStay repeats during the intersection
• OnTrigger events are useful to detect intersections between colliders
• The Collider.gameObject property can be checked to know what did one hit

What is the difference between traditional movement and physics-based movement, and how are physics forces added?

• Traditional movement occurs on update with the transform component. Physics movement occurs during FixedUpdate with the Rigidbody component
• The most common way to add physics force is with the Rigidbody.AddForce () method
• Using the ForceMode of force is most common for gradual movement which respects mass

What are ways to manipulate physics properties and what are common use cases?

• Many physics properties can be set in both the Unity Inspector and with C# code
• A common use of isKinematic and useGravity is to toggle on and off physics for a specific GameObject
• A common use of IsSleeping is to check if a GameObject has come to rest

What are spatial queries and why are they useful in gaming?

• Spatial queries project a Ray (line) or a Collider (shape) through space to judge distances and potential future collisions
• A common use case for raycasting is to detect what could be in front of your GameObject
• A common use case of RaycastCommand is to run many raycast operations async and in parallel to improve game performance

Why is physics debugging important and what are the tools available?

• Physics is highly complex and resource intensive, so optimization is important to improve game performance
• Debug.DrawRay() is useful to visualize certain operations in the editor and to quality-assure the project
• The Physics Debugger and Profiler window are useful to inspect the performance impact of physics solutions with an eye toward improvement

How do we proceed from initial inspiration to planning a game project?

• First, use the inspiration for reference and pick the parts we want to use
• Next, breakdown the project into major tasks
• Lastly, we completely open Unity, and set up the project structure and scene hierarchy

How do we take user input and create projectile motion?

• First, use the mouse input from the user to aim
• Next, use Rigidbody.AddForce() to create projectile motion
• Lastly, isolate key gameplay variables for easy tweaking

How do we create a flexible system of various game obstacles?

• First, create a WorldItem concept with OnCollision events and health
• Next, send out damage events and use that to update graphics
• Lastly, tweak the resistance to damage to give a good difficulty level

ow do we decide when the game end, for example, win and loss?

• First, decide the rules of the game
• Next, implement those rules in code using gaming paradigms like score and lives
• Lastly, create a UI (text/images) to communicate the rules and the result (win and loss)

What is polish and how do we add it to please the users?

• Polish is the input, animation, and graphics used to make a good game great
• Identify the aspects of our game that need polish
• Add easy-to-implement fades and tweens to please the eye

How do we proceed from initial inspiration to planning a game project?

• First, use the inspiration for reference and pick the parts you want to use
• Next breakdown the project into major tasks
• Lastly, open Unity and set up the project structure and scene hierarchy

How do we take user input and create physics motion?

• First, use the keyboard input from the user
• Next, use Rigidbody.AddForce() to create physics motion
• Lastly, isolate key gameplay variables for easy tweaking

How do we create a flexible system of various game obstacles?

• First, plan for the types of objects in the world and decide on behavior
• Next, create movable and immovable objects
• Lastly, do the level design to create a fun and challenge

How do we decide when the game ends? for example (win and loss)

• First, decide on the rules of the game
• Next, implement those rules in code using gaming paradigms like score and time
• Lastly, create a UI (text/images) to communicate the rules and the result (win and loss)

What is polish and how do we add it to please the users?

• Polish is the input level design and input, used to make a good game great
• Identify aspects of our game that need polish
• Add easy-to-implement fades and tweens to please the eye

What the, best practices for physics projects to help ease development and scale your projects?

• Use only 2D physics for 2D games and only 3D physics for 3D games
• Use physics as it was intended, including moving via physics forces
• Be aware of which operations are processor intensive and avoid them

How do you get the best performance in your physics projects?

• Use the latest version of Unity for the best performance
• Adjust physics settings like Time.fixedDeltaTime and Physics.sleepThreshold to optimize performance
• Use primitive colliders instead of mesh colliders for efficient runtime playback

How can you predict the path of a Rigidbody?

• When prediction is needed, include it early in development, for best results
• Move your object with physics forces
• Use the separate UnityEngine.PhysicsScene to run the predictive calculations

What is Unity DOTS and how will it impact the future of Unity physics?

• The Data-Oriented Technology Stack (DOTS) offers high performance by default
• DOTS features include the C# Job System, the (ECS) pattern for writing code, and the burst compiler for optimization
• The future of Unity Physics with DOTS represents blazing fast speed improvements